Driving mechanism



June 5, 1928. l s 1,672,677

Y A. L. ELLIS DRIVING" MECHANISM Filed July 14, 1925 Hmwumm n I l I ll ll ll ll lm inventor": Alvarado LR. Ellis,

His Attorney.

Patented 1m 5, 1928.

UNITED STATES PATENT oFFleE.

anvmnon MASSACHUSETTS, ASSIGNOB '20 em nnrvnre Application ma m, 14, ms. Serial m. 43,020.

My invention relates to driving mechi anism and has for its ob'ect the provision of means for'dri" an-o ject with great ac-v curacy from ano er object. 6' More specifically my invention has for its object a driving connection wherem errors due'to flex'ure of the various partsof'the drivin mechanism are avoided. .erny force applied to a mechanical part, such as a 1 shaft, gear, lever, etc., produces a flexure m that part which of course, varies w1th the magnitude of the applied force. Where great accuracy is demanded this becomes an important consideration for the error due to 1'5 flexure alone, in addition to inaccuracies 1n construction, may well exceed the maximum allowable error in the driving connect on.

My invention has .particular apihcatlon where a speed ratiois introduce by. the driving connection, and it is necessary to apply the driving. force to the low speed end of the driving connection, such 'for example as in the driving of an indicator or motlon transmitting device at many times the speed of a drivin object, such as a telescope. In this case it is obvious that a relatively lar e driving force mustbe 'ap lied not only m order to drive the object, ut also to overcome the inertia in starting of the ob ect so fvarious parts of the driving connection.

In carrying out m invention, provide a driving motor for t e driven obJect, whlch motor is controlled in response to the flexure of the driving" connection in such manner that the drivingconnection is relieved of a lar part of the required driving force and its xure thereby reduced. For a more complete understanding of my invention refeignce shoilhd llimili to the accompanying rawmg,- e sing e gure o which is a diagrammatic view showmg drivin mechanism embodying my invention. fieferring to-the dra a high speed driven object, at a high spee ratio with respect to a telescope Orsifihtrng so device 11 constituting a low divmg As shown the transmitt' device is connected" by a driving gear tram 12 to I have shown; 5' my invention in one form as applied to the of an angular motion transmitting device 10 of any suitable form, constituting.

the telesco e so as to be actuated in a pre- I determine high speed ratio with the movements of the telescope about a normally vertical axis. This axis may be defined by a driving shaft 13 secured to the telescope to which the shaft 14 of the transmitting device -is connected by the gear train 12. The drivin ratio of the gear train 12 may, for examp e, be 72:1.

"It will be seen that the force which must be applied to the telescope 11 in order to turn the shaft 14 of the transmitting dewoe is multiplied in roportigmto the driving ratio, and in a dition'there must be added the friction and the inertia of the various parts. This driving force causes flexure of various parts,.pa'rticularly those low speed parts closely associated with the telesco e. Due to this flexure' it ma be posslb e to turn thetelescope throng an appreciable angle before rotation of the duc ed. Where great accuracy is an imporshaft 14 of the tranimitting device is protant consideration it s evident that such an arrangement would be impracticable.

In accordance with, my invention I provide a suitable driving motor 15, shown as a shunt wound electric motor, which is connected'directly to the shaft 14 .of the transmitting device by means of a gear 16 on the shaft of the motor which meshes with the gear 17 on the shaft 14. This motor drives the transmitting device, and it is controlled automatically by virtue of the flexure of the variousparts of the driving connection between the telescope and the transmitting de-- vice of'which the ar train 12 forms a part. A gear train 18 o relativelyllight construction is driven by the telescope 11. The driving ratio of this gear train 'is the same as the driving ratio of the gear train 12, or the Same as the driving who of a'certain portion of the gear train 12.. .The' shaft 19 is driven by the gear train 18 through reversing gears 18 at the same speed as-theshaft 20 is driven by-the gear train 12, the' shaft 20 bein connected to the ar train '12 at the hi h'speed end of this gear train or near t at. end. The shafts 19 and 20 are connected to bevelled gears 21'and 22 respec- .tively forming part of a conventional type 21 and 22 cooperate with similar bevelled gears 23 and 24 which are carried by a ring 1 gear 25. This-ring gear 25 drives the gear 26 to which is secured a contact arm 27 moving between two stationary contacts 28 and I 29 whereby-the circuit of themotor 1 is biased by their own weight. into engagecontrolled.

The contact arm 27 controls two pivoted contact arms 30 and 31 in thearmature circuit ofthe motor. These contact arms are are connected through conductors 39 and 40- to the armature terminals of the motor. The field of the motor is connected to the mains 35 and36 by means of the conductors 41 and 42.

The contact arms 30 and 31 are actuated by means of magnet coils 43 and 44. One

terminal of each of the coils 43 and 44 is connected through a conductor 45 to the supply main 35. The remaining terminal of the coil 43 is connected to the contact 29,

while the remaining terminal of thecoil 44 is connected to the contact 28. The contact arm 27 is electrically insulated from its su porting or driving parts and is electrical y connected through conductor 46 to the supply main 36. Y

" other As thus constructed and arranged the operation of my invention is as follows When a turning 'force is ap lied to the telesco e 11 a certain amount 0 flexure will be pro uced in the driving gear train 12 and arts associated with it before 'a su'flicient orce has been applied to the shaft to operate the transmitting device. This turningofthe telescope 11 independently of the transmitting devlce is transmitted through the light ear train -18 and the differential device to t e contact arm 27, since'this'drivmg connection has, but a very small force to transmit in moving thecontact arm 27 and furthermore since the various parts are of verylight construction and have but little nertia. The control means for the motor 1s so arranged that the independent movement of the telescope reduced b the application of a force w 'ch is on y a very small part of that which would be re uired to dr1ve the transmitting device is su cient to move the contact arm 27 into engagement with one or other of the-contacts 28 and 29, and thus start the motor. It will be observed that when the contact arm 27 en-' gages the contact 28 the coil 44 is energized in the opposite direction the contact arm 27 engages the contact 29 whereby the coil 43- is energized and the contact arm 30 moved into engagement with the central contact 37 to start the motor in the opfposite direction. As long as the driving orce is applied to the telescope and the contact 27 thereby maintained in engagement with one or the other of its contacts, the motor 15 will be -in operation to drive the transmitting vdevice. As soon as this driving force is removed, however,the contact arm 27 breaks the control circuit and the contact arm 30 or 31, as the case may be, immediately moves into engagement with the contact 32 or .33

in accordance with its bias. In this -position of the contact arms 30 and 31, which is shown in the drawing, the armature of the.

motor is short circuited and the motor is thereby brought quickly to rest by dynamic braking. It should be understood that in this spec1- ficat-ion and the appended clalms, I use the terms low speed and high speed in a relative sense only. The motion of the transmitting device 10 may be quite slow as compared with the motion of otherwell-known objects ordinarily termed thigh speed, but as compared with the telescope, the transmitting device is driven at hlgh speed, and conversely as compared with the transmitting device, the telescope moves at low speed.

' WhileI have described my invention as embodied in concrete form and as operatingin a specific manner in accordance with the revisions of the patentstatutes, it should e understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art vwithout departing from the spirit of my invention, the scope oi which is setforthin the annexed clalms. f

What I claim as new and desire tosecure by Letters Patent of the United States is .1. Means for driving an object from an-' other object comprising a gear train forming a driving connection between said obects, a driving motor operatlvely connected tosaid driven object, and means responsive to flexure of said motor.

2,. Means "for driving an object athi h speed with respect to another object Ey means of a force applied to the low speed ob- .gect comprising a gear train forming ,a drivmg connection between said objects, a motor gear train for starting said.

for driving said high speed'object, control means for said motor, and a driving connection between said control means and said low speed object whereby said motor is started upon flexure of said gear train.

3. Means for driving an object at high speed with respect to another object y means of a force apfiilied to the low speed object com rising a eavy gear train forms mg a mec anical connection between said ob ects, a motor for driving said high speed object, a relativel light gear train connected to said low speed for said motor actuated by said light gear train to start the motor upon flexure of said heavy gear train.

4. Means for driving one object from another object comprising a mechanical driving connection between said objects, a relatively light driving connection connected to said driving object and operating means for said driven object controlled Jointly by said driving connections in accor ance with the I relative displacement of said objects due to flexure of said driving connection.

5. Means for driving one object from another object comprising a gear train forming a driving connection between said objects, a relatively light gear train connected to said driving object, and operatin means for said driven object controlled jointly by said gear trains in accordance with the relaobject, and control means,

tive displacement of said objects due to flexure of said driving connection.

6. Means for driving a motion transmitting device at high speed with respect to a driving object,'compr1sing a gear train forming a mechanical connection between said transmitting device and said drivin object, a motor for driving said transmlttin device, a relatively light gear train connecte to the driving ob ect, and control means for said motor actuated by said gear trains, whereby said motor is started by said light gear train upon independenhmovement of said driving object due to flexure of said 'gear train connection.

7. Means for driving an object at high speed from another object, comprising a high speed ratio gear train connecting said objects, an electric driving motor, a driving connection between said motor and said high speed object, control means for said motor, and an operating connection between said control means and said low speed object whereby said motor is started upon flexure of said gear train to drive said high speed object in a direction to followsald low speed ob ect. v 1

In witness whereof, I have hereunto set my hand this 10th day of July, 1925.

ALVARADO L. R. ELLIS. 

